Some New Features in Moto-Vehicle
Design by Thomas Hugh ParkerFrom the March 1899 edition of The
Automotor and Horseless Vehicle Journal

An Excerpt from a paper
read before the Liverpool Self-Propelled Traffic Association
by Mr. Thomas Hugh Parker, on 28th February 1899

Some two and a half years ago, I was spending my time supervising the
erection of electrical and general plant in the Transvaal goldfields.
and the necessity for an efficient motor controller often presented
itself to me. After giving some considerable time and thought to the
problem, I obtained a satisfactory result, and communicated the idea, by
means of drawings, to my father, Mr. Thomas Parker, at Wolverhampton,
for use in the factory. Soon after this, I heard the pleasing news that
a Bill was to be presented to Parliament to allow of mechanical road
locomotion in England, and was not long in grasping the fact that the
controller would also adapt itself to controlling electrical road
vehicles. Fired with this idea, and wishing to be in the first swim of a
new industry, I started for England, and immediately after my arrival in
Wolverhampton set to work designing an electric car.

I selected a section of road over which it was obvious the car would
have to run, viz., between my father's house at Tettenhall and the town
of Wolverhampton, a distance of 2.5 miles without a single yard of level
ground in its length, the gradients varying from 1 in 120 to 1 in 15.
The first difficulty that presented itself was to obtain data to work
upon. My idea was that 12 cwt. would be more than a reasonable. weight
to allow for an unloaded electric car for six passengers, and the
nearest article I could find of this weight as my father's brougham. I
procured a large spring balance, and set out at daybreak to map out a
curve of -the force required to draw the brougham over the track. We
took the shafts off and attached the horse with the spring balance
inserted between the animal and the vehicle, and not until that December
morning had I fully realised the power of a horse, although I have had
to deal with them nearly all my life. My dream of 12 cwt. was at an end,
for, after carefully working out all points, the weight totalled up to a
minimum of 25 cwt. for a three hours' run at eight miles per hour.

Figure 1. A small electric dog-cart with
double bogie steering. Courtesy of the late Jim Boulton.

Having determined the approximate power required, the next most important
problem was the design of the motor and gearing. After a great deal of
discussion amongst the members of the family, it was decided that it
would be preferable to use two motors coupled by means of single or
double reduction gear, running in oil, ever required, to the hind
wheels, in preference to using a single motor and differential gear.
Double spur gearing did not work in well with the design, the result of
which decision was that chains had to be used on the second reduction,
necessitating the use of eccentrics for taking up the slack or stretch
of the chains, and two frames to support the motors separately.

These first motors were series wound, and designed to run at 950 revs.
per minute, and give a torque effort of 30 lbs. on the periphery of each
armature with a current of 25 amperes. Forty was chosen as the number of
cells, to permit of their being charged in series on the usual 110 volt
circuit. The controlling of the car came next. To do this without the
use of resistance coils was adifficult matter at first, but eventually turned out to be one of the
simplest. Three speeds forward and one backward were found to meet all
requirements, and these variations were obtained by dividing the cells
into two groups of 20 each. The three forward movements were obtained as
follows: First, by putting batteries in parallel, motor series, giving
two milesper hour; second, batteries series, motor
series, four miles per hour; and third, batteries series, motors
parallel, eight miles per hour. The one backward movement, batteries
parallel, motor series, with current in the armatures reversed, two
miles per hour. The whole of the operations were carried out, by means
of the controller mentioned at the beginning of this paper with less
than one single turn of the handle.

The steering gear presented itself next. I had heard a great deal of
what bad been done, and had seen a car with Ackermann gear, but was
dissatisfied with it, and also the double cycle head arrangement. I
wanted a steering gear that would admit of a car running round a small
circle with as little resistance as going straight ahead, and, after a
great deal of scheming devised the idea of moving both front and hind
wheels in opposite directions at the same time and through the same
angle, which, both in model and practical form, worked splendidly. It
enabled the car to be turned in its own length without turning the
wheels under the body, and is naturally double as sensitive as a single
bogie or broken axle gear. Another great advantage is that it admits of
all four wheels being driven, and the load being equally divided on all
four wheels. It gives a good support to the bottom of the vehicle, which
in most cases is made quite flat. Each wheel can be provided with a
brake.

A careful examination was made of the various types of batteries, and
it was decided to give the Blot Company the order for the first set.
Having overcome the various points of difficulty on paper, some premises
were rented in which it was just possible to build and put the car
together, and as the weight of the car grew we had to shore the floor up
from beneath. Six weeks from the day we commenced, the car was ready to
be launched. I say launched, because it had to be lowered 18 inches into
the square down some planks.

Somehow the news leaked out that a trial was to
take place, and we found a large crowd of people waiting outside
when the doors were taken down, as there was not sufficient room to
open them when the car was inside. You may judge from this how much
chance we had to make a private trial. However, she was launched and
ran a 10 mile trip, with nine people aboard, without a hitch. During
the journey we had occasion to descend some very stiff gradients,
and I found, although I bad some powerful brakes upon the car, it
was with great difficulty I could restrain it from getting the
better of me.

Figure 2. A view of the bottom of the small
double bogie car with axles turned to their extreme angle. Courtesy
of the late Jim Boulton.

Although I did not say anything to the passengers, I decided before the
journey was finished not to attempt another trip with series motors. I
had the motors dismounted and had them shunt wound, and, needless w say,
had to stand a good deal of chaff for such a thing, as running shunt
motors in conjunction with storage batteries on tramways had years ago
been green up as impracticable. The motors were hung on the third day,
the connections were made, and the car run clown into the street, the
result being beyond expectation. Instead of the sudden rush of current
as at starting with the series motors, viz., 50 amperes, the car moved
steadily away with less than 10 amperes, although the current was about
the same when the rate of travelling accelerated. We then proceeded to
take some tests on an incline. To do this we ran the double journey to
Tettenhall and back. The work of manipulating the car was very much
reduced, it only being necessary to set it to the required speed and
look out for obstacles. On descending the stiffest hill the speed did
not increase 5 per cent., and it was very gratifying to see the ampere
meter reading 20 amperes to the good, charging the batteries instead of
wearing the brake blocks away. In case of need it was found possible to
bring the car to a stand from full speed ahead in 3 feet on a 10 per
cent. Gradient, without the use of the brake or reversing the motors.
This original car has been running almost daily for the past 18 months
exactly as it was made, without a single breakdown, and has carried some
of the most eminent men of the century upon it.

I will now proceed to describe a few lantern slides I have had prepared
under difficulties for you, showing the various stages of progress.

Figure 3. A 14 seater omnibus. Courtesy of
the late Jim Boulton.

The original controller is adapted for use with
shunt motors working on ordinary high tension circuits, to enable
three movements to be made consecutively with one handle, locking
and interlocking each movement. There are two rollers or discs fixed
to the centre spindle, actuating two levers connected to the two
switches, top and bottom. In starting from zero, the one disc, which
is slightly in advance of the other, first puts on the shunt switch
and locks it on, leaving the handle free to turn a full revolution
in the same direction.

The next portion of the revolution puts on the main switch and locks it
on, allowing the main current to flow through the armature with
resistance in the circuit. This resistance is determined by the switch
arm carried on the centre spindle below the discs working on an ordinary
divided resistance ring, and, in this case, admits 24 points of
regulation in a single turn of the handle. When stopping the motor, it
follows that the maximum resistance must be put into the circuit ready
for starting. Again, the main current must be broken before it is
possible to break the shunt, thereby avoiding all danger of burning out
the armature, which would be the case if the shunt were broken first.
Further, if the motor has to be stopped and started often, as in the
case of hauling machinery or hoists, cranes, and the like, the shunts
can be left on, as shown, by which arrangement no damage is done to the
insulation by the high voltage due to induction on breaking shunt
circuits.

In the controller as adapted to the electric cars the spindle carries
five discs connected to levers projecting from discs. From each of these
discs project eight teeth, which connect with eight bars, which are
connected to the batteries and motors. The whole of the five movements
are obtained in about three-quarters of a revolution of the handle, and
each movement is locked and interlocked in its proper order. Figure 1 is
a small electric dog-cart with double bogie steering, driven by the
front wheels, and double reduction through differential gear.

Figure 4. An experimental oil-car climbing a gradient of
1 in 6. Courtesy of the late Jim Boulton.

Figure 2 shows a view of the bottom of the small
double bogie car with axles turned to their extreme angle. We were
asked by the. London Electric Omnibus Company (Limited) to design
and build them an electric omnibus. They had made three or four
attempts, under Mr. Ward's direction, but had not been rewarded with
much success. I had already had some experience with the car
carrying nine passengers, and I went to London to see Ward's omnibus
run. The car that had run so successfully with us weighed 30 cwt.
unloaded, and carried nine people.

Ward's omnibus weighed, with 24 passengers on, something like 7.5 tons.
I saw that their difficulty was in the enormous weight, and decided to
build one not to exceed 3.5 tons loaded with 14 passengers, driver, and
conductor (Figure 3). This was constructed on the double-bogie principle
having the batteries under the seats. It has two motors, one on each
bogie, driving all four wheels. To each of the four wheels has been
attached a powerful hydraulic brake working by means of a force pump
near the driver's seat. The vehicle has three speeds forward and one
backward, it will turn in its own length, has only two handles to
manipulate it, and will run over ordinary roads 25 miles with one charge
at a mean speed of eight miles an hour.

Figure 4 shows an oil-car climbing a gradient of 1 in 6, upon which it
is just as easily manipulated as upon the level, stopping, starting,
backing, and going forward at the will of the driver, and without the
aid of a brake.